OCR A level Biology Question - thanks

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Mentor05
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#1
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Hey,

Please can someone help me with this question. I always struggle with these. Any tips, suggestions or steps would be so helpful. Thank you
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rw77
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Hi,
Unfortunately I cannot see the units or numbers clearly to give you a precise measurement. I presume for question a) the volume decreased because the expiratory reserve volume is now lower than the inspiratory reserve volume. This means the person is inhaling more than exhaling, but there seems to be some sort of air leakage. Possible the diaphragm relaxed so lung pressure increases due to rib cage closing in, so the lung cannot be expanded. Aka shortness of breath.


e) in order to know/detect exercise is to see the tidal volume (breath in and out in one cycle) increasing to show rapid breaths for oxygen supply to meet oxygen demand.

If you struggle with these type of questions i suggest watching short videos with a graph next to it, to show the person breathing in and out, with labelled terms eg. vital capacity.

I hope that helps : )
Last edited by rw77; 6 months ago
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Mentor05
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#3
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(Original post by rw77)
Hi,
Unfortunately I cannot see the units or numbers clearly to give you a precise measurement. I presume for question a) the volume decreased because the expiratory volume is now lower than the inspiratory volume. This means the person is inhaling more than exhaling, but there seems to be some sort of air leakage. Possible the diaphragm relaxed so lung pressure increases due to rib cage closing in, so the lung cannot be expanded. Aka shortness of breath.


e) in order to know/detect exercise is to see the tidal volume (breath in and out in one cycle) increasing to show rapid breaths for oxygen supply to meet oxygen demand.

If you struggle with these type of questions i suggest watching short videos with a graph next to it, to show the person breathing in and out, with labelled terms eg. vital capacity.

I hope that helps : )
Hey, thanks so much! The x axis is time measured in second and the y axis is volume in spirometer measured in dm^3. I have attached a clearer picture. Also. What would you write for this question?

What ways would you expect the trace to change if they started to exercise? (3) it’s for the same graph

This is my answer so far:
During exercise, tidal volume increases as the depth of breathing increases and the rate of breathing increases too. This has the effect of taking more oxygen into the body and removing more carbon dioxide. The changes in breathing rate, tidal volume and respiratory minute ventilation reflect increased gas exchange during exercise due to the increased demand for energy in skeletal muscles. The supply of oxygen to the tissues is increased where more oxygen is needed for aerobic respiration. The increased oxygen consumption reflects the increased rate of respiration in the tissues. More energy is made available for muscle contraction during exercise.
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rw77
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Oh ok great, I will look at them thanks. Your explanation for e) is written coherently with the right terms , however I do suggest adding some useful terms since the questions points in reference to the graph, you want to probs mention the trace will have a higher frequency and amplitude since the tidal volume is rapidly increasing. The vital capacity also remains the same (because that's the maximum amount of air that can leave the lungs after breathing in as much as possible) . so pls include parts of the graph to help you remain in the specificity of the question, as it states 'what ways would you expect the trace to change'

Aside from that, great job explaining the effects of the exercise on the body. :congrats:
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Mentor05
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(Original post by rw77)
Oh ok great, I will look at them thanks. Your explanation for e) is written coherently with the right terms , however I do suggest adding some useful terms since the questions points in reference to the graph, you want to probs mention the trace will have a higher frequency and amplitude since the tidal volume is rapidly increasing. The vital capacity also remains the same (because that's the maximum amount of air that can leave the lungs after breathing in as much as possible) . so pls include parts of the graph to help you remain in the specificity of the question, as it states 'what ways would you expect the trace to change'

Aside from that, great job explaining the effects of the exercise on the body. :congrats:
Thanks so much, this is very helpful!
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rw77
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hi,
I got 0.6 dm3- 0.5dm3 for the tidal volume

Ventilation rate = tidal volume x breathing rate/respiratory rate (amount of breaths aka peaks/troughs you can count in one second)

so 0.6 x 11 breaths per minute= 6.6 or a lower value depending on the range you choose for the tidal volume.

Oxygen consumption
The image below perfectly explains it than me lol: just think of it like a histogram measuring the area to get the frequency density.

https://practicalbiology.org/images/...-trace-500.jpg
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